Liquid pigment dispersion and curative agents

ABSTRACT

A liquid pigment dispersion is disclosed. The dispersion comprises a pigment dispersed in a blend of two or more active hydrogen-containing materials that together have a freezing point that is room temperature or below. The pigment remains dispersed in the blend, even if the dispersion is subjected to freezing and thawing. A curative blend comprising at least two active hydrogen-containing materials, which is liquid at room temperature, is also disclosed. The dispersions and curative blends of the present invention can be solvent-free. Resins and prepolymers comprising the curative blends of the invention, either pigmented or unpigmented, are also disclosed.

FIELD OF THE INVENTION

The present invention is directed to a liquid, storage stable pigmentdispersion. More specifically, the pigment dispersion contains a blendof active hydrogen-containing materials, which can serve as curativeagents for various resins.

BACKGROUND INFORMATION

Polyurethanes, polyureas and other isocyanate-containing resins arewidely used in numerous industries. These resins typically come in twocategories, thermoset and thermoplastic. They are usually coreacted withan active hydrogen-containing material, such as an amine or glycol, toeffect cure; this is particularly true for thermosets.

Some curing agents used in polyurethane and/or polyurea compositionshave relatively high freezing points, which makes shipping and storageof these materials during the winter season problematic. The problem iscompounded when the compositions include pigments. When certaincurative/pigment blends have thawed from a frozen state, the solidsseparate and the quality of the pigment dispersed therein can be lost,as measured by the Hegman scale. The Hegman scale is a measurement ofparticle size, which is typically used to denote the degree of pigmentdispersion. When a material completely loses its quality of dispersion(Hegman equals zero), the particle size of the material is generallyabout 100 microns or greater. Such a separated blend would need to beredispersed before it could be used. In cases where the pigment hasundergone “hard settling”, the pigment cannot be redispersed and theblend is unusable.

There remains a continuing need for curative agents, particularly thosein which a pigment is dispersed, that can withstand lower storage andshipping temperatures. In addition, it would be advantageous to providesuch agents that, even if they became frozen, can be thawed and usedwithout the need to redisperse the pigment; it would be furtheradvantageous to provide such agents that do not experience anysubstantial change or sacrifice in the properties they impart to theprepolymer or resin into which they are incorporated.

SUMMARY OF THE INVENTION

The present invention provides a liquid pigment dispersion comprising apigment dispersed in a blend of two or more active hydrogen-containingmaterials. Each of the active hydrogen-containing materials may have adifferent freezing point; this encompasses embodiments in which thefreezing points of the materials are different and embodiments in whichthe freezing points of the materials are the same. The combined freezingpoint of the active hydrogen-containing materials, however, will be suchthat the pigment dispersion is liquid at room temperature, that is 68°F. to 77° F., down to about 55° F. This range of temperatures, i.e. roomtemperature to 55° F., is referred to herein as “room temperature andbelow”.

It is significant that the present pigment dispersions are liquid atroom temperature and below, and in many embodiments at even lowertemperatures, and furthermore that they are storage stable over a widertemperature range than other curative materials. “Storage stable”, asused herein, refers to the ability of a dispersion, blend, compositionor the like to resist freezing at temperatures down to about 55° F., andalso refers to the ability of these compositions to maintain theirproperties even if they become frozen. For example, the storage stabledispersions, blends, and compositions of the present invention can befrozen to temperatures of down to −15° F. or lower, and still be usable,when thawed, without the need to redisperse. For example, thedispersions, blends and other embodiments of the present invention havebeen found to maintain their pigment dispersion quality even afterfreezing, and to retain their curative properties even if frozen. Inaddition, dispersions, blends and other embodiments of the presentinvention that have undergone a freeze/thaw cycle will still impart thesame desirable properties to the prepolymers and resins into which theyare incorporated, such as adhesive strength, shear/cut resistance, shorehardness, durability and the like. This is significant, as many curativematerials comprising pigment lose their pigment dispersion quality uponfreezing. For example, a blend of 1,4-butanediol and pigment will loseits pigment dispersion if frozen and thawed. Such pigment dispersions,when frozen and thawed, will require redispersion before they can beused, if they can even be used at all.

It will be understood by those skilled in the art that pigmentdispersion is typically evaluated in terms of the “Hegman scale”. Asdiscussed above, the Hegman scale is a measure of particle size. TheHegman scale denotes the fineness of the dispersed pigment, i.e., thedegree of dispersion and consistency of particle size. The scale runsfrom zero wherein the particle size is >100 microns, to eight whereinthe particle size is too small to measure in microns. The measurement istaken by drawing down a sample on a grind block, the face of which issurfaced such that particles of a certain size will visibly protrude onthe block at the designated intervals. A poor quality pigment dispersion(i.e. a Hegman measurement of less than 4) would denote that the pigmentparticles are large or that there are large agglomerates, which maylimit the application of the dispersion. A good quality pigmentdispersion (i.e. a Hegman measurement of 4 or greater) indicates apigment dispersion that is widely usable in many applications.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a liquid pigment dispersioncomprising a pigment dispersed in a blend of two or more activehydrogen-containing materials, wherein each active hydrogen-containingmaterial may have a different freezing point. In addition to beingliquid at room temperature and below, the present pigment dispersionsare also storage stable.

Any pigment can be used according to the present invention, absentcompatibility problems. A particularly suitable pigment is titaniumdioxide (TiO₂). Titanium dioxide can be particularly difficult tomaintain in dispersion because it is often used in high concentrations;also, because of its relatively high density, it is prone to settling.Other pigments include but are not limited to inorganic pigments such asred or yellow iron oxides, carbon black, and ultramarine blue, andorganic pigments such as phthalocyanine blues and greens, carbazoleviolets, and naphthol reds.

Alternatively, the pigment can be in the form of a premade colorant ortint, such as those commercially available from Polyone Corporation.These premade colorants or tints typically contain a pigment or pigmentsdispersed in a grind vehicle. The grind vehicles can be, for example, ahigh molecular weight polyol, dipropylene glycol dibenzoate, diethyleneglycol adipate or other suitable compounds. It will be understood thatcertain grind vehicles may introduce small quantities of activehydrogen-containing groups to the present compositions; these quantitiesare not significant (i.e. <5% of the total active hydrogen groups) andare not included in the weight percents of active hydrogen-containingmaterials discussed below. Thus, any weight ratios, percentages or thelike provided herein do not include active hydrogen-containinggroups/materials that may be contributed by the grind vehicle. It willbe further understood that many grind vehicles have very limitedfunctionality or will be nonfunctional.

As noted above, the pigment is dispersed in a blend of activehydrogen-containing materials. An active hydrogen-containing material isone that contains a hydrogen that is reactive; such materials might havean active hydrogen, for example, by having a hydroxyl, primary amino,secondary amino or thiol group. The active hydrogen-containing materialsare generally describable as monomers or oligomers, rather than polymersor resins. “Monomer” will be understood as referring to molecules orcompounds having a relatively low molecular weight and a simplestructure capable of conversion to a polymer, resin or elastomer bycombination with itself or other similar molecules or compounds. Anoligomer is a combination of only a few (i.e. 4 or less) monomers. Apolymer, in contrast, comprises 5 or more of such units. For example,the active hydrogen-containing materials can have a number averagemolecular weight of between about 30 and 4000, such as between about 90and 1000. The blend can include two or more of such materials. Eachactive hydrogen-containing material may have a different freezing point,and in many embodiments, each active hydrogen-containing material willhave a different freezing point. For example, one activehydrogen-containing material can be solid at room temperature, whileanother active hydrogen-containing material in the blend can be liquidat room temperature. Any active hydrogen-containing materials can beused together in any amounts according to the present invention, so longas they are compatible, and so long as their combined freezing point issuch that the resulting blend is liquid at room temperature and below.For example, the freezing point of the blend can be 60° F. or less, 55°F. or less, or 50° F. or less. In one embodiment, the activehydrogen-containing materials are selected so that the resultingdispersion is storage stable if the dispersion is subjected totemperatures below which it will freeze.

Specific examples of active hydrogen-containing materials includehydrogen-terminated compounds, such as diols or glycols. Diols having anodd number of carbon atoms may be particularly suitable, as may be diolshaving a pendant methyl group. Examples include, but are not limited to,ethylene glycol; diethylene glycol; polyethylene glycol; propyleneglycol; 2-methyl-1,3-propanediol (“MPD”), 2-methyl-1,4-butanediol(“MBD”); dipropylene glycol; polypropylene glycol; 1,2-butanediol;1,3-butanediol; 1,4-butanediol (“BDO”); 2,3-butanediol;2,3-dimethyl-2,3-butanediol; trimethylolpropane; cyclohexyldimethylol;triisopropanolamine; tetra-(2-hydroxypropyl) ethylene diamine;diethylene glycol di-(aminopropyl)ether; 1,5-pentanediol;1,6-hexanediol; 1,3-bis-(2-hydroxyethoxy) cyclohexane;1,4-cyclohexyldimethylol; 1,3-bis-[2-(2-hydroxyethoxy) ethoxy]cyclohexane; 1,3-bis-{2-[2-(2-hydroxyethoxy) ethoxy] ethoxy}cyclohexane; polytetramethylene ether glycol having a molecular weightranging from about 250 to about 3900;resorcinol-di-(beta-hydroxyethyl)ether and its derivatives;hydroquinone-di-(beta-hydroxyethyl)ether and its derivatives;1,3-bis-(2-hydroxyethoxy) benzene; 1,3-bis-[2-(2-hydroxyethoxy) ethoxy]benzene; N,N-bis(β-hydroxypropyl) aniline;2-propanol-1,1′-phenylaminobis; and mixtures thereof. Thehydroxy-terminated active hydrogen-containing material may have amolecular weight of at least about 50. In one embodiment, the molecularweight of the hydroxy-terminated active hydrogen-containing material isabout 2000 or less. In yet another embodiment, the hydroxy-terminatedactive hydrogen-containing material has a molecular weight of about 250to about 3900. It should be understood that molecular weight, as usedherein, is the absolute weight average molecular weight as would beunderstood by one of ordinary skill in the art.

Active hydrogen-containing materials according to the present inventioncan also include amine-terminated compounds. Suitable amine-terminatedcompounds include, but are not limited to, ethylene diamine;hexamethylene diamine; 1-methyl-2,6-cyclohexyl diamine;tetrahydroxypropylene ethylene diamine; 2,2,4- and2,4,4-trimethyl-1,6-hexanediamine;4,4′-bis-(sec-butylamino)-dicyclohexylmethane;1,4-bis-(sec-butylamino)-cyclohexane;1,2-bis-(sec-butylamino)-cyclohexane; derivatives of4,4′-bis-(sec-butylamino)-dicyclohexylmethane; 4,4′-dicyclohexylmethanediamine; 1,4-cyclohexane-bis-(methylamine);1,3-cyclohexane-bis-(methylamine); diethylene glycoldi-(aminopropyl)ether; 2-methylpentamethylene-diamine;diaminocyclohexane; diethylene triamine; triethylene tetramine;tetraethylene pentamine; propylene diamine; 1,3-diaminopropane;dimethylamino propylamine; diethylamino propylamine;imido-bis-propylamine; monoethanolamine; diethanolamine;triethanolamine; monoisopropanolamine, diisopropanolamine;triisopropanolamine; isophoronediamine;4,4′-methylenebis-(2-chloroaniline);3,5-dimethylthio-2,4-toluenediamine;3,5-dimethylthio-2,6-toluenediamine; 3,5-diethylthio-2,4-toluenediamine;3,5-diethylthio-2,6-toluenediamine;4,4′-bis-(sec-butylamino)-diphenylmethane and derivatives thereof;1,4-bis-(sec-butylamino)-benzene; 1,2-bis-(sec-butylamino)-benzene;N,N′-dialkylamino-diphenylmethane;trimethyleneglycol-di-p-aminobenzoate;polytetramethyleneoxide-di-p-aminobenzoate;4,4′-methylenebis-(3-chloro-2,6-diethyleneaniline);4,4′-methylenebis-(2,6-diethylaniline); meta-phenylenediamine;paraphenylenediamine; cyclohexyldimethol; and mixtures thereof. In oneembodiment, the amine-terminated active hydrogen-containing material is4,4′-bis-(sec-butylamino)-dicyclohexylmethylene. In another embodiment,the amine-terminated active hydrogen-containing material has a molecularweight of about 64 or greater. In yet another embodiment, the molecularweight of the amine-terminated active hydrogen-containing material isabout 2000 or less.

In one embodiment, when one of the active hydrogen-containing materialsis an alcohol having a molecular weight less than 200, the other activehydrogen-containing material is not a dihydroxy compound having amolecular weight of between 204 and 500 and having an ester group. Inanother embodiment, the blends, dispersions and compositions of thepresent invention specifically exclude dimethyl sulfoxide.

It will be appreciated that many of the active hydrogen-containingmaterials listed above have relatively high freezing points, and aretherefore solid at room temperature. For example, BDO has a freezingpoint of 68° F., hexamethylene diamine of 105.8° F., diethanolamine of82.4° F., triethanolamine of 69.8° F., diisopropylamine of 73.4° F. andtriisopropylamine of 111.2° F. Other listed diols and amines havefreezing points less than room temperature, some considerably less. Forexample, MDP has a freezing point of −65° F., ethylene glycol of 9° F.,dipropylene glycol of −58° F. and propylene glycol of −74° F. It will beappreciated that when various combinations of these diols and/or aminesare blended, the freezing point of the blend will be such that the blendis liquid at room temperature and below, and in some cases even lower.Any combination or blend of active hydrogen-containing materials, notlimited to those listed above, can be used according to the presentinvention, again so long as the freezing point of the blend is such thatthe dispersion is liquid at room temperature and below. It is within theskill of one practicing in the art to determine the freezing point of ablend using freezing point determination methods standard in the art. Anempirical method of freezing point determination is to cool the sample,such as by surrounding it with an ice bath while stirring, and to recordthe temperature at regular intervals, such as every minute, until thematerial begins to solidify. As solidification occurs, the temperaturebegins to level off. This temperature is the freezing point. Analyticalmethods such as calorimetry, such as Differential Scanning Calorimetry(DSC), may also be used.

The present blends can comprise active hydrogen-containing materialsthat are all liquid at room temperature, or one or more that are liquidat room temperature and one or more that are solid at room temperature.In this latter embodiment, the material(s) that are liquid at roomtemperature can be used in an amount sufficient to reduce the freezingpoint of the material(s) that are solid at room temperature, such thatthe blend is liquid at room temperature and below. In one embodiment,the liquid at room temperature material is added to the solid at roomtemperature material in an amount of about 8 percent or greater byweight of the blend, such as in an amount of about 10 percent or greaterby weight, or in an amount of about 12 percent or greater by weight, oreven 14 percent or greater by weight of the blend. The “weight of theblend” refers only to the weight of the active hydrogen-containingmaterials. A particularly suitable embodiment includes 90 weight percentof a material that is solid at room temperature, such as BDO, and 10percent by weight of a material that is liquid at room temperature, suchas MPD or MBD. It will be appreciated that often a relatively minorportion of the blend need be liquid at room temperature in order toachieve the liquid, storage stable characteristics of the overalldispersion. This allows the present compositions to retain the excellentproperties obtained with the solid at room temperature curative agents,without needing to worry about those agents solidifying or losing theirHegman grind if solidification occurs.

The pigment of the present invention generally comprises about 10 to 70weight percent, such as about 15 to 55 weight percent, or about 20 to 25weight percent, with weight percent being based on the total weight ofthe liquid pigment dispersion. The active hydrogen-containing materialblend typically comprises about 30 to 90 weight percent of the totalformula, such as about 50 to 80 weight percent, or about 70 weightpercent, with weight percent being based on the total weight of theliquid pigment dispersion. In addition, the liquid pigment dispersionsof the present invention can further comprise additional additivesstandard in the art in a weight percent of up to about 10, again withweight percent being based upon the total weight of the dispersion.Suitable additives include, for example, wetting additives, lightstabilizers and catalysts. Wetting additives would be added to moreeffectively disperse the pigment or pigments, and are commerciallyavailable from Byk-Chemie, Crompton Corporation, and others. Lightstabilizers would be added to prevent photo-degradation upon exposure tothe environment and are commercially available from Ciba, Cytec, andothers. Hindered amine light stabilizers are particularly suitablebecause they will react with UV light that reaches the surface of thematerial, converting it to thermal energy, thus slowing anyphoto-degradation. A catalyst can be added to accelerate cure time;suitable catalysts are commercially available from Air ProductsCorporation. Particularly suitable for use in the present invention aretin-containing catalysts.

It will be appreciated that the liquid pigment dispersions of thepresent invention can be formulated so as to be solvent-free.“Solvent-free”, as used herein, means 1 weight percent or less ofsolvent, such as water, alcohol, ketones, aromatic solvents, esters, andthe like.

It will be appreciated that the active hydrogen-containing materialsdiscussed above find particular application as curative agents forresins containing isocyanate groups, such as polyurethanes andpolyureas. Accordingly, the present invention is further directed to acurative blend comprising a first active hydrogen-containing materialand a second active hydrogen-containing material, wherein the freezingpoint of the blend is less than 68° F. Any active hydrogen-containingmaterial, such as the hydroxy-terminated and/or amine terminatedmaterials described above, can be used. Such curative blends can furthercomprise additional active hydrogen-containing materials and/or any ofthe pigments or additives discussed above, and can also be formulated tobe essentially solvent-free. Any suitable polyurethane or polyureacomposition can be cured with the liquid pigment dispersion or curativeblend of the present invention.

It will be appreciated that polyurethane-based resins according to thepresent invention can be prepared by reacting at least one polyurethaneprepolymer and the dispersion or curative agent described above; thepolyurethane prepolymer will be understood as being a product formed bya reaction between at least one polyol and at least one diisocyanate.The resins need not be formed through the use of a prepolymer, however;any method known in the art can be used. In one embodiment, thepolyurethane-based compositions of the invention are saturated and, thuscomprise the reaction product of at least one saturated polyurethaneprepolymer formed from at least one saturated diisocyanate and at leastone saturated polyol, and a liquid pigment dispersion or curative blendof the present invention that contains at least one saturated activehydrogen-containing material.

Any isocyanate known in the art is suitable for use with thepolyurethane prepolymer, including aliphatic, cycloaliphatic,araliphatic, derivatives thereof, and combinations of these compoundshaving two or more isocyanate (NCO) groups per molecule. The isocyanatesmay be organic, modified organic, organic polyisocyanate-terminatedprepolymers, low free isocyanates, and mixtures thereof. Theisocyanate-containing reactable component may also include anyisocyanate-functional monomer, dimer, trimer, or multimeric adductthereof, prepolymer, quasi-prepolymer, or mixtures thereof.Isocyanate-functional compounds may include monoisocyanates orpolyisocyanates that include any isocyanate functionality of two ormore. Suitable isocyanate-containing components include diisocyanateshaving the generic structure O═C═N—R—N═C═O, where R is preferably acyclic, linear or branched hydrocarbon moiety containing from about 1 to20 carbon atoms. The diisocyanate may also contain one or more cyclicgroups or one or more phenyl groups. When multiple cyclic groups arepresent, linear and/or branched hydrocarbons containing from about 1 to10 carbon atoms can be present as spacers between the cyclic or aromaticgroups. In some cases, the cyclic or aromatic group(s) may besubstituted at the 2-, 3-, and/or 4-positions. Substituted groups mayinclude, but are not limited to, halogens, primary, secondary, ortertiary hydrocarbon groups, or a mixture thereof.

Examples of saturated diisocyanates that can be used in the polyurethaneprepolymer include, but are not limited to, ethylene diisocyanate;propylene-1,2-diisocyanate; tetramethylene diisocyanate;tetramethylene-1,4-diisocyanate; 1,6-hexamethylene-diisocyanate (“HDI”);octamethylene diisocyanate; decamethylene diisocyanate;2,2,4-trimethylhexamethylene diisocyanate; 2,4,4-trimethylhexamethylenediisocyanate; dodecane-1,12-diisocyanate; dicyclohexylmethanediisocyanate; cyclobutane-1,3-diisocyanate;cyclohexane-1,2-diisocyanate; cyclohexane-1,3-diisocyanate;cyclohexane-1,4-diisocyanate; methyl-cyclohexylene diisocyanate(“HTDI”); 2,4-methylcyclohexane diisocyanate; 2,6-methylcyclohexanediisocyanate; 4,4′-dicyclohexyl diisocyanate; 2,4′-dicyclohexyldiisocyanate; 1,3,5-cyclohexane triisocyanate;isocyanatomethylcyclohexane isocyanate;1-isocyanato-3,3-5-trimethyl-5-isocyanatomethylcyclohexane;isocyanatoethylcyclohexane isocyanate; bis(isocyanatomethyl)-cyclohexanediisocyanate; 4,4′-bis(isocyanatomethyl) dicyclohexane;2,4′-bis(isocyanatomethyl)dicyclohexane; isophoronediisocyanate(“IPDI”); triisocyanate of HDI; triisocyanate of2,2,4-trimethyl-1,6-hexane diisocyanate (“TMDI”);4,4′-dicyclohexylmethane diisocyanate (“H₁₂MDI”); 2,4-hexahydrotoluenediisocyanate; 2,6-hexahydrotoluene diisocyanate; aromatic aliphaticisocyanate, such 1,2-, 1,3-, and 1,4-xylene diisocyanate;meta-tetramethylxylene diisocyanate (“m-TMXDI”); para-tetramethylxylenediisocyanate (“p-TMXDI”); trimerized isocyanurate of any polyisocyanate,such as isocyanurate of toluene diisocyanate, trimer of diphenylmethanediisocyanate, trimer of tetramethylxylene diisocyanate, isocyanurate ofhexamethylene diisocyanate, and mixtures thereof; dimerized uredione ofany polyisocyanate, such as uredione of toluene diisocyanate, uredioneof hexamethylene diisocyanate, and mixtures thereof; modifiedpolyisocyanate derived from the above isocyanates and polyisocyanates;and mixtures thereof. In one embodiment, the saturated diisocyanatesinclude IPDI, H₁₂MDI, HDI, or a combination thereof.

Examples of unsaturated diisocyanates that can be used according to thepresent invention include, but are not limited to, substituted andisomeric mixtures including 2,2′-, 2,4′-, and 4,4′-diphenylmethanediisocyanate (“MDI”); 3,3′-dimethyl-4,4′-biphenylene diisocyanate(“TODI”); toluene diisocyanate (“TDI”); polymeric MDI;carbodiimide-modified liquid 4,4′-diphenylmethane diisocyanate;para-phenylene diisocyanate (“PPDI”); meta-phenylene diisocyanate(“MPDI”); triphenyl methane-4,4′-, and triphenylmethane-4,4″-triisocyanate; naphthylene-1,5-diisocyanate; 2,4′-, 4,4′-,and 2,2-biphenyl diisocyanate; polyphenyl polymethylene polyisocyanate(“PMDI”); mixtures of MDI and PMDI; and mixtures of PMDI and TDI.

Any saturated polyol available to one of ordinary skill in the art issuitable for use in the polyurethane prepolymer. Exemplary polyolsinclude, but are not limited to, polyether polyols, polycaprolactonepolyols, polyester polyols, polycarbonate polyols, hydrocarbon polyols,and mixtures thereof. Suitable saturated polyether polyols for use inthe present invention include, but are not limited to,polytetramethylene ether glycol (“PTMEG”); PTG-L; poly(oxyethylene)glycol; poly(oxypropylene) glycol; poly(ethylene oxide cappedoxypropylene) glycol; and mixtures thereof.

Saturated polycaprolactone polyols include, but are not limited to,diethylene glycol initiated polycaprolactone; propylene glycol initiatedpolycaprolactone; 1,4-butanediol initiated polycaprolactone; trimethylolpropane initiated polycaprolactone; neopentyl glycol initiatedpolycaprolactone; 1,6-hexanediol initiated polycaprolactone; PTMEGinitiated polycaprolactone; and mixtures thereof.

Suitable saturated polyester polyols include, but are not limited to,polyethylene adipate glycol; polyethylene propylene glycol; polybutyleneadipate glycol; polyethylene butylene adipate glycol; polyhexamethyleneadipate glycol; polyhexamethylene butylene adipate glycol; and mixturesthereof. An example of a polycarbonate polyol that may be used with thepresent invention includes, but are not limited to, poly(hexamethylenecarbonate) glycol.

Hydrocarbon polyols include, but are not limited to, hydroxy-terminatedliquid isoprene rubber (LIR), hydroxy-terminated polybutadiene polyol,saturated hydroxy-terminated hydrocarbon polyols, and mixtures thereof.Other aliphatic polyols that may be used to form the prepolymer of theinvention include, but are not limited to, glycerols; castor oil and itsderivatives; Kraton polyols; acrylic polyols; acid functionalizedpolyols based on a carboxylic, sulfonic, or phosphoric acid groups;dimer alcohols converted from the saturated dimerized fatty acid; andmixtures thereof.

The number of unreacted NCO groups in the polyurethane prepolymer may bevaried to control such factors as the speed of the reaction, theresultant hardness of the composition, and the like. For instance, thenumber of unreacted NCO groups in the polyurethane prepolymer ofisocyanate and polyol may be less than about 14 percent. In oneembodiment, the polyurethane prepolymer has from about 5 percent toabout 11 percent unreacted NCO groups, such as from about 6 to about 9.5percent unreacted NCO groups. In one embodiment, the percentage ofunreacted NCO groups in the polyurethane polymer may be about 7.5percent or less, such as about 7 percent or less. In another embodiment,the unreacted NCO content is from about 2.5 percent to about 7.5percent, such as from about 4 percent to about 6.5 percent.

The compositions of the invention may also be polyurea-based, which aredistinctly different from polyurethane compositions, but also result indesirable characteristics when used in similar applications. Thepolyurea-based compositions are saturated in one embodiment.

Without being bound to any particular theory, it is now believed thatsubstitution of the long chain polyol segment in the polyurethaneprepolymer with a long chain polyamine oligomer soft segment to form apolyurea prepolymer improves shear, cut, and resiliency, as well asadhesion to other components. The polyurea compositions of the presentinvention may be formed from the reaction product of an isocyanate andpolyamine prepolymer crosslinked with the dispersion or blend of thepresent invention. Again, prepolymers need not be used. For example,polyurea-based compositions of the invention may be prepared from atleast one isocyanate, at least one polyether amine, and a liquid pigmentdispersion or curative blend of the present invention.

Any polyamine available to one of ordinary skill in the art is suitablefor use in the polyurea prepolymer. Polyether amines are particularlysuitable for use, especially in the “prepolymer” embodiment. As usedherein, “polyether amines” refer to at least polyoxyalkyleneaminescontaining primary amino groups attached to the terminus of a polyetherbackbone. Due to the rapid reaction of isocyanate and amine, and theinsolubility of many urea products, the selection of diamines andpolyether amines may be limited to those allowing the successfulformation of the polyurea prepolymers. In one embodiment, the polyetherbackbone is based on tetramethylene, propylene, ethylene,trimethylolpropane, glycerin, and mixtures thereof.

Suitable polyether amines include, but are not limited to,methyldiethanolamine; polyoxyalkylenediamines such as polytetramethyleneether diamines, polyoxypropylenetriamine, and polyoxypropylene diamines;poly(ethylene oxide capped oxypropylene) ether diamines; propyleneoxide-based triamines; triethyleneglycoldiamines;trimethylolpropane-based triamines; glycerin-based triamines; andmixtures thereof. In one embodiment, the polyether amine used to formthe prepolymer is JEFFAMINE D2000, commercially available from HuntsmanCorporation of Austin, Tex.

The molecular weight of the polyether amine for use in the polyureaprepolymer may range from about 100 to about 5000, such as 200 orgreater, or about 230 or greater. In another embodiment, the molecularweight of the polyether amine is about 4000 or less, such as about 3000or less. In yet another embodiment, the molecular weight of thepolyether amine is about 600 or greater. In yet another embodiment, themolecular weight of the polyether amine is about 1000 to about 3000,such as about 1500 to about 2500. Because lower molecular weightpolyether amines may be prone to forming solid polyureas, a highermolecular weight oligomer, such as JEFFAMINE D2000, is often moresuitable.

In one embodiment, the polyether amine has the generic structure:

wherein the repeating unit x has a value ranging from about 1 to about70, such as from about 5 to about 50, or about 12 to about 35.

In another embodiment, the polyether amine has the generic structure:

wherein the repeating units x and z have combined values from about 3.6to about 8 and the repeating unit y has a value ranging from about 9 toabout 50, and wherein R is —(CH₂)_(a)—, where “a” may be a repeatingunit ranging from about 1 to about 10.

In yet another embodiment, the polyether amine has the genericstructure:H₂N—(R)—O—(R)—O—(R)—NH₂wherein R is —(CH₂)_(a)—, and “a” may be a repeating unit ranging fromabout 1 to about 10.

As briefly discussed above, some amines may be unsuitable for reactionwith the isocyanate because of the rapid reaction between the twocomponents. In particular, shorter chain amines are fast reacting. Inone embodiment, however, a hindered secondary diamine may be suitablefor use in the prepolymer. Without being bound to any particular theory,it is believed that an amine with a high level of stearic hindrance,e.g., a tertiary butyl group on the nitrogen atom, has a slower reactionrate than an amine with no hindrance or a low level of hindrance. Forexample, 4,4′-bis-(sec-butylamino)-dicyclohexylmethane (CLEARLINK 1000,commercially available from UOP corporation) may be suitable for use incombination with an isocyanate to form the polyurea prepolymer.

Any isocyanate available to one of ordinary skill in the art is suitablefor use in the polyurea prepolymer. Suitable isocyanates are describedabove with reference to the polyurethane composition.

The polyurethane and polyurea prepolymers, if used, may be formed withthe liquid pigment dispersions or curative blends described above, whichcan include, for example, hydroxy-terminated materials, amine-terminatedmaterials, and mixtures thereof. Accordingly, the present invention isfurther directed to polyurethane and polyurea prepolymers so formed.

Depending on the type of curatives in the dispersion/blend, thepolyurethane composition may be thermoplastic or thermoset in nature.For example, polyurethane prepolymers cured with a diol or secondarydiamine with 1:1 stoichiometry are thermoplastic in nature. Thermosetpolyurethanes, on the other hand, are generally produced from aprepolymer cured with a primary diamine or polyfunctional glycol.

In addition, the type of curative(s) in the dispersion/blend determinewhether the polyurethane composition is polyurethane-urethane or apolyurethane-urea. For example, a polyurethane prepolymer cured withhydroxy-terminated materials is polyurethane-urethane because any excessisocyanate groups will react with the hydroxyl groups to create moreurethane linkages. In contrast, if an amine-terminated material is usedwith the polyurethane prepolymer, the excess isocyanate groups willreact with the amine groups to create urea linkages.

It will be appreciated that the liquid pigment dispersions of thepresent invention can be made in at least two different ways. In thefirst method, a pigment is incorporated by blending, such as with acowles grind or a mill grind, into a blend of active hydrogen-containingmaterials. The pigment can be added to a first-activehydrogen-containing material, and the second or more active hydrogenmaterials can be added later, or all of the active hydrogen-containingmaterials can first be blended, and the pigment added thereto.Alternatively, a pigment commercially available in a grind vehicle canbe mixed in with the active hydrogen-containing blend of the presentinvention; again, the pigment/grind vehicle can be added to a firstactive hydrogen-containing material and the second or more activehydrogen materials can be added later, or the pigment/grind vehicle canbe added to all of the active hydrogen-containing materials that havealready been blended. In this embodiment, simple mixing would be used;because the pigment is already dispersed in the grind vehicle, therewould be no need to grind the pigment in with the blend. In eitherembodiment, the standard additives, if used, can be added at any time.

As used herein, unless otherwise expressly specified all numbers such asthose expressing values, ranges, amounts or percentages may be read asif prefaced by the word “about”, even if the term does not expresslyappear. Plural encompasses singular and vice versa. Also, as usedherein, the term “polymer” is meant to refer to oligomers and bothhomopolymers and copolymers; the prefix “poly” refers to two or more.

EXAMPLES

The following examples are intended to illustrate the invention, andshould not be construed as limiting the invention in any way. Weightpercents are based upon the total weight of the formulation.

Example 1

Pigment dispersions according to the present invention were preparedusing the components listed in Tables 1 and 2, as indicated: TABLE 1Percent by weight Material of total formula 1,4 Butanediol¹ 69.44%Titanium Dioxide White Pigment² 23.42% Ultramarine Blue Pigment³ 0.23%SILWET L-7210 wetting additive⁴ 0.10% Hindered Amine Light Stabilizer⁵2.13% Tin Catalyst⁶ 4.68%¹Obtained from Ashland Chemical.²Obtained from Dupont Corp.³Obtained from Whittaker, Clark, and Daniels⁴Polyalkeneoxide modified polydimethylsiloxane, obtained from CromptonCorp.⁵TINUVIN 292, obtained from Ciba Geigy.⁶Dibutyl Tin Dilaurate, obtained from Air Products.

The pigments were dispersed by means of a Cowles blade to a Hegman grindof 6.0. This product, referred to as Component A below, was furtherblended with a second active hydrogen-containing component, “ComponentB” as shown in Table 2. TABLE 2 % by weight 1,4 % by weight of BDO % ofComponent by Component Component Freezing Sample A weight B B point⁷ 1100%  69.4% none 0 64° F. 2 90% 62.5% Ethylene 10% 45° F. Glycol 3 90%62.5% Dipropylene 10% 50° F. Glycol 4 90% 62.5% Propylene 10% 50° F.Glycol 5 90% 62.5% 2-methyl-1,3 10% 50° F. propanediol⁷Freezing point was determined by cooling the material in an ice bathand recording the temperature at which solidification was first noticed.

It was visually observed in Sample 5 that the blend was not only lowerin freezing point than the original curative blend, but it also formed asoft semi-solid rather than crystallizing.

As can be seen in Table 2, the blends comprising only 10 weight percentof Component B served to considerably lower the freezing point of thepigment dispersion.

Example 2

A titanium white pigment dispersion, using a tin catalyst for fasterreaction, was prepared by first making a paste, referred to as ComponentC below, with the following components: TABLE 3 Percent by weightMaterial of total formula 1,4 Butanediol 53.78% TiO₂ White Pigment46.02% SILWET L-7210 wetting additive 0.20%

The pigment was dispersed by means of a Cowles blade to a Hegman grindof 6.0. The paste was then formulated into a blend according to thepresent invention with the following components: TABLE 4 1,4 ComponentBDO % 2-methyl,1-3 C by propanediol Tin Catalyst Freezing Sample % byweight weight % by weight % by weight point 6 57.3% 37.5% 0 5.3% 66° F.7 57.3% 36.8% 0.7% 5.3% 66° F. 8 57.3% 34.1% 3.4% 5.3% 58° F. 9 57.3%30.7% 6.8% 5.3% 53° F. 10  57.3% 23.8% 13.6%  5.3% 42° F.

It was visually observed that Samples 9 and 10 were not only lower infreezing point than Sample 6, with BDO alone, but they also formed asoft semi-solid rather than crystallizing. Also, greater than 0.7 weightpercent of MPD was needed to affect the freezing point of the blend.

Samples 6-10 were kept in a freezer for 72 hours, where the temperatureranged between −14° F. and +14° F. The samples were then thawed at roomtemperature and the pigment dispersion was measured upon thawing. Table5 lists the Hegman value after one freeze-thaw cycle. TABLE 5 Hegmanbefore Sample freezing: Hegman after freezing: 6 6.0 0 with largeagglomerates 7 6.0 0 with large agglomerates 8 6.0 0 with lessagglomerates 9 6.0 4.0 very smooth, homogenous 10 6.0 5.0 very smooth,homogenous

As shown in Table 5, Samples 9 and 10 were usable after freezing andthawing without having to redisperse the pigment via high speedagitation or mill grinding.

Example 3

An organic red pigment dispersion, referred to as Component D below, wasprepared by making a paste using the following components: TABLE 6Percent by weight Material of total formulation 1,4 Butanediol 78.26%Novoperm Red Pigment⁸ 21.60% SILWET L-7605 wetting additive 0.14%⁸Obtained from Clariant Corp.

The pigment was dispersed by means of a Cowles blade to a Hegman grindof 5.0. The paste was then formulated into a blend according to thepresent invention with the following components: TABLE 7 2-methyl,1-3Component D 1,4 BDO % by propanediol Freezing Sample % by weight weight% by weight point 11 66.7% 33.3% 0 66° F. 12 66.7% 32.5% 0.8% 66° F. 1366.7% 29.1% 4.2% 58° F. 14 66.7% 24.8% 8.5% 53° F. 15 66.7% 16.2% 17.1% 42° F.

It was visually observed that Samples 14 and 15 were not only lower infreezing point than Sample 11, with BDO alone, but they also formed asoft semi-solid rather than crystallizing.

Samples 11-15 were kept in a freezer for 72 hours, where the temperatureranged between −14° F. and +14° F. The samples were then thawed at roomtemperature and the pigment dispersion was measured upon thawing. Table8 illustrates the Hegman grind after one freeze-thaw cycle run. TABLE 8Hegman grind Sample before freezing: Hegman grind after freezing: 11 5.00 with large agglomerates 12 5.0 0 with large agglomerates 13 5.0 0 withless agglomerates 14 5.0 4.0 very smooth, homogenous 15 5.0 5.0 verysmooth, homogenous

As shown in Table 8, Samples 14 and 15 were usable after freezing andthawing without having to redisperse the pigment through high speedagitation or mill grind.

Example 4

A pre-manufactured white-violet colorant, HCC-15181 white-violetdispersion from Polyone Corporation, was used for this example. Thecolorant contains titanium dioxide white, a small amount of carbazoleviolet 23, and a high molecular weight polyol grind vehicle. TheHCC-15181 was formulated with polytetramethylene ether glycol (PTMEG)(weight average molecular weight 1000), and 1,2-butanediol (freezingpoint, −173° F.) as shown in Table 9. TABLE 9 HCC-15181 PTMEG 1000 1,2Butanediol Freezing Sample % by weight % by weight % by weight Point 1616.7% 83.3%   0% 64° F. 17 16.7% 82.5% 0.8% 58° F. 18 16.7% 79.2% 4.1%58° F. 19 16.7% 75.0% 8.3% 58° F. 20 16.7% 66.6% 16.7%  58° F.

All of the samples were homogenous in appearance after freezing; novisible separation or crystallization was seen.

Whereas particular embodiments of this invention have been describedabove for purposes of illustration, it will be evident to those skilledin the art that numerous variations of the details of the presentinvention may be made without departing from the invention as defined inthe appended claims.

1-31. (canceled)
 32. A prepolymer formed from the reaction between adiisocyanate, a polyol and/or a polyamine, and a pigment dispersion,wherein the pigment dispersion is liquid at room temperature and belowand comprises a pigment dispersed in a blend of two or more activehydrogen-containing materials, wherein each active hydrogen-containingmaterial may have a different freezing point.
 33. A polyurethaneprepolymer formed from the reaction between a diisocyanate, a polyol,and a curative blend comprising: (a) a first active hydrogen-containingmaterial and (b) a second active hydrogen-containing material, whereinthe active hydrogen-containing materials have different freezing points,and the freezing point of the blend is 60° F. or less.
 34. Theprepolymer of claim 32, wherein said prepolymer is saturated. 35-36.(canceled)
 37. The prepolymer of claim 33, wherein the diisocyanate isdiphenylmethane diisocyanate and the polyol is polyalkylene glycol. 38.The prepolymer of claim 36, wherein the diisocyanate is4,4′-dicyclohexylmethane diisocyanate and the polyamine is polyalkylenediamine.
 39. The prepolymer of claim 32, wherein the prepolymer is apolyurethane prepolymer.
 40. The prepolymer of claim 32, wherein theprepolymer is a polyurea.
 41. The prepolymer of claim 33, wherein theprepolymer is a polyurethane prepolymer.
 42. The prepolymer of claim 33,wherein the prepolymer is a polyurea.
 43. The prepolymer of claim 32,wherein each active-hydrogen containing material has a differentfreezing point.
 44. The prepolymer of claim 43, wherein a first activehydrogen-containing material is solid at room temperature and a secondactive hydrogen-containing material is liquid at room temperature.